Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit be3e83e3 authored by Boris Brezillon's avatar Boris Brezillon Committed by Brian Norris
Browse files

mtd: nand: atmel: Relax tADL_min constraint 



Version 4 of the ONFI spec mandates that tADL be at least 400 nanoseconds,
but, depending on the master clock rate, 400 ns may not fit in the tADL
field of the SMC reg. We need to relax the check and accept the -ERANGE
return code.

Note that previous versions of the ONFI spec had a lower tADL_min (100 or
200 ns). It's not clear why this timing constraint got increased but it
seems most NANDs are fine with values lower than 400ns, so we should be
safe.

Fixes: f9ce2edd ("mtd: nand: atmel: Add ->setup_data_interface() hooks")
Signed-off-by: default avatarBoris Brezillon <boris.brezillon@free-electrons.com>
Tested-by: default avatarQuentin Schulz <quentin.schulz@free-electrons.com>
Signed-off-by: default avatarBrian Norris <computersforpeace@gmail.com>
parent b974696d

drivers/mtd/nand/atmel/nand-controller.c

+12 −1
Original line number Diff line number Diff line
@@ -1364,7 +1364,18 @@ static int atmel_smc_nand_prepare_smcconf(struct atmel_nand *nand, 
	ret = atmel_smc_cs_conf_set_timing(smcconf,

					   ATMEL_HSMC_TIMINGS_TADL_SHIFT,

					   ncycles);

	if (ret)

	/*

	 * Version 4 of the ONFI spec mandates that tADL be at least 400

	 * nanoseconds, but, depending on the master clock rate, 400 ns may not

	 * fit in the tADL field of the SMC reg. We need to relax the check and

	 * accept the -ERANGE return code.

	 *

	 * Note that previous versions of the ONFI spec had a lower tADL_min

	 * (100 or 200 ns). It's not clear why this timing constraint got

	 * increased but it seems most NANDs are fine with values lower than

	 * 400ns, so we should be safe.

	 */

	if (ret && ret != -ERANGE)

		return ret;



	ncycles = DIV_ROUND_UP(conf->timings.sdr.tAR_min, mckperiodps);